U.S. patent number 4,650,061 [Application Number 06/815,671] was granted by the patent office on 1987-03-17 for crowding lug transfer conveyor system.
This patent grant is currently assigned to Weyerhaeuser Company. Invention is credited to Earl D. Hasenwinkle, Frank Wislocker.
United States Patent |
4,650,061 |
Hasenwinkle , et
al. |
March 17, 1987 |
Crowding lug transfer conveyor system
Abstract
A crowding lug transfer conveyor system has an infeed and an
outfeed end with a primary conveyor surface serving to a convey
pieces therebetween. A plurality of lugs, each slideably mounted on
a lug chain, are held at the infeed end and then released ahead of
an incoming piece. An upstanding member on the lug is above the
plane of the primary surface and the lug body is below the plane. A
predetermined body length establishes the spacing and crowding
distance at the outfeed end. Escapement mechanisms serve to release
individual lugs on command both at the infeed and outfeed ends. At
the outfeed end a plurality of lugs and pieces may be accumulated
and spaced with the pieces then being metered in a singulated
controlled manner. Caliper blocks in the lugs serve to grasp the
lug chain when a lug is released with the lug chain continuously
passing through the caliper blocks when the lug is being held in
place awaiting release.
Inventors: |
Hasenwinkle; Earl D. (Puyallup,
WA), Wislocker; Frank (Sumner, WA) |
Assignee: |
Weyerhaeuser Company (Tacoma,
WA)
|
Family
ID: |
27016060 |
Appl.
No.: |
06/815,671 |
Filed: |
January 2, 1986 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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718815 |
Apr 1, 1985 |
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397955 |
Jul 14, 1982 |
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Current U.S.
Class: |
198/462.3;
198/465.1 |
Current CPC
Class: |
B27B
31/00 (20130101); B65G 47/31 (20130101); B65G
37/00 (20130101) |
Current International
Class: |
B27B
31/00 (20060101); B65G 47/31 (20060101); B65G
37/00 (20060101); B65G 047/31 (); B65G
047/84 () |
Field of
Search: |
;198/459,460,461,462,472,478,648,465.1,469.1,473.1,803.01,803.2
;83/435.1 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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2253632 |
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May 1974 |
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DE |
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1428753 |
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Jan 1966 |
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FR |
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2311734 |
|
Jan 1977 |
|
FR |
|
11581 |
|
Jan 1977 |
|
JP |
|
Primary Examiner: Valenza; Joseph E.
Assistant Examiner: Alexander; Daniel R.
Parent Case Text
This application is a continuation of application Ser. No.
06/718,815, filed 4/01/85, now abandoned, which is a continuation
of application Ser. No. 06/397,955, filed 07/14/82, now abandoned.
Claims
We claim:
1. In a crowding lug transfer conveyor including an infeed end and
an outfeed end with a primary conveyor surface therebetween
including means for depositing pieces atop the conveyor surface at
the infeed end and for accepting the pieces downstream from the
outfeed end, the improvement comprising:
at least one endless chain adapted to be continuously driven and
having its top run below the plane of the primary conveyor surface
and extending between the infeed and outfeed ends,
a plurality of lugs mounted about the endless chain and moveable
with respect thereto in a slidable relationship and having
upstanding members extending upwardly above the plane of the
primary conveyor surface as a lug is moving with its endless chain
along the top run, said lugs having body portions with a
predetermined length to establish a predetermined spacing between
the upstanding members when two or more lugs are abutting one
another.
at least one front and one back pair of opposed caliper blocks on
each lug having means for frictionally engaging the blocks against
the sides of the endless chain thereby causing the lug to travel
until a force counteracts the frictional gripping force allowing
the chain to slide relative to the caliper blocks, said caliper
blocks being pivotally mounted on the lugs,
means at the infeed end to hold and then release individual lugs to
travel with its endless chain toward the outfeed end, and
means at the outfeed end to hold and then release individual lugs
to travel with its endless chain back to the infeed end.
2. The improvement as in claim 1 including a plurality of endless
chains spaced from each other with each chain having a plurality of
lugs mounted thereon adapted to function as spaced apart sets of
lugs.
3. The improvement as in claim 2 further including means for
tensioning the endless chains and maintaining the tension within a
predetermined tension range.
4. The improvement as in claim 2 further including guide means
associated with the lugs for causing the lugs to travel in a
predetermined path.
5. The improvement as in claim 2 in which the means for holding and
releasing the lugs at the infeed and outfeed ends comprise rotary
escapement plates driven on command for impeding, conveying, and
releasing lugs.
6. The improvement as in claim 5 in which the escapement plates
operate to release one set of lugs causing them to travel with
their respective endless chains to the infeed or outfeed end where
they will be held until released.
Description
BACKGROUND OF THE INVENTION
This invention relates generally to material handling and more
specifically to conveying and accumulation of work pieces such as
boards or cants in a sawmill.
In modern high-speed sawmills, a typical example of an environment
where the invention can be applied, logs are typically broken down
into a plurality of separate elongated pieces at the machine center
known as the primary breakdown system. As logs have been
diminishing in size over the years, particularly in the diameter
dimension, high-speed systems have necessarily been developed to
maintain production and economic requirements. High-speed in-line
breakdown processes are necessary; however, at the breakdown
stations, separate pieces are simultaneously generated and they
must be handled efficiently for further processing.
Typically, the primary breakdown system will generate at least one
center cant and side boards, as well as slabs. A center cant is an
elongated piece having two flat sides generated by saw lines and
two curviliner surfaces being portions of the surface of the log.
Cants are then normally directed to a secondary breakdown station
where a plurality of individual pieces will be generated, usually
having sizes approximating finished lumber sizes. While the cants
from the primary breakdown station can continue in line to the
secondary cant breakdown station, it is more common for them to
undergo a lateral transfer before reaching the secondary cant
breakdown station. It is the lateral transfer function where the
present invention may be utilized within the sawmill
environment.
Side boards are similar to cants in that they normally have two
flat surfaces and two curvilinear surfaces, although they are
generally thinner and normally proceed to a secondary board
breakdown station known as an edger. At the edgers, the side boards
are fed linearly through the secondary breakdown system where the
two curvilinear side edges are removed either by sawing means or
chipping means. The boards flowing out of an edger will usually
have a cross-sectional size approximating the finished lumber size.
Just as cants normally undergo a lateral transfer from the primary
breakdown station, side boards are also transferred laterally to an
edging station before being fed linearly through the edger. Slabs,
having one flat surface and one curvilinear surface, can be
processed in a manner similar to cants and side boards with respect
to material handling, specifically via a lateral transfer system to
a secondary slab breakdown station where available boards can be
generated from the slabs.
A problem in a sawmill in the past has been material handling
associated with the high piece counts in the lateral transfer
functions. In order to generate maximum production at the primary
breakdown station, it is necessary to process the optimum number of
logs per unit of time. In modern high-speed mills, piece counts
through the primary breakdown system may approach ten per minute.
In a typical high-speed facility, if two side boards are generated
from each log, the side board material handling and downstream
processing system would necessarily be designed to process twenty
side boards per minute. Since side boards are elongated and
difficult to handle, the piece count needed to be handled is a
difficult problem. Oftentimes, with such a high piece count, the
boards accumulate too rapidly and overlap, thereby causing pileups,
severe skewing and jam-ups. Unscramblers were necessary to attempt
to continuously handle the pieces and singulate them for efficient
processing at the edger.
In order for the edger to operate at its optimum production
capacity, individual side boards must be available continuously at
the edger infeed station in a singulated, even-ended and non-skewed
orientation. The consequences from inefficient handling in a
lateral transfer function are downtime while removing jam-ups and
lower productivity through the secondary breakdown stations.
Similar problems occurred in the cant lateral transfer function, as
well as with the lateral transfer function for slabs. Ideally, side
boards, cants and slabs will be available to the infeed station of
each respective machine center in a singulated, even-ended and
non-skewed orientation on a continuous basis. To ensure such a
supply of elongated pieces at each machine center, a crowding and
accumulating means is desirable in the lateral transfer function so
that on demand there is always a properly oriented piece for
movement into the respective machine center. By continuously having
an accumulated supply of singulated and properly spaced elongated
pieces ahead of each machine center's infeed station, then each
machine center can operate at its optimum production capacity.
Accordingly, from the foregoing, it is an object of the present
invention to reduce material handling problems in a transfer
conveyor.
It is a further object to increase productivity through a
downstream processing station.
It is yet another object to increase the productivity of an
upstream processing station by reducing downtime from downstream
material handling problems.
It is still a further object to provide an accumulation of pieces
ahead of a processing station in a proper singulated, even-ended,
and non-skewed orientation so that continuous flow can proceed
through the processing station.
These and many other objects of the present invention will become
apparent upon reading the detailed description to follow in
conjunction with the attached drawings.
SUMMARY OF THE INVENTION
Briefly stated, the present system invention is practiced in one
form by positioning an endless lug chain about sprockets with the
sprockets being mounted at the infeed end and the outfeed end of a
crowding lug transfer conveyor. The crowding lug conveyor
incorporates a plurality of lugs slidably mounted on the endless
chain and each has an upstanding lug plate mounted on a uniformly
sized spacer body with guide pins and caliper blocks on the body.
The plane of the endless chain and spacer bodies is just below the
plane of the primary conveyor surface supporting the pieces in the
transfer conveyor. The spacer bodies have a length dimension that
is designed to be greater than the average width dimension of the
pieces to be transferred, crowded and metered from the outfeed end.
Escapement mechanisms are mounted adjacent the sprockets to hold
and index the lug assemblies on command. Upon release at the infeed
end, the caliper blocks will, by friction, allow a lug assembly to
travel with its endless chain. At the outfeed end, the escapement
mechanism operates to meter a piece to the downstream process by
causing the lugs to again be indexed, one at a time from those
crowded together at the outfeed end. The lugs return from the
outfeed end to the infeed end on the endless lug chain where they
are held ready for indexing below the plane of the primary conveyor
surface. At the outfeed end, a number of individual pieces can be
crowded together in a spaced manner and then metered one by one to
the next downstream processing station. The present distance
between adjacent upstanding lug plates normally provides a uniform
spacing between pieces and therefore more efficient transfer and
handling.
DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view showing the overall arrangement of the
crowding lug transfer conveyor in a typical environment.
FIG. 2 is a side elevation at the outfeed end showing detail of the
slideable lugs and escapement mechanism.
FIG. 3 is a sectional view taken along line 3--3 of FIG. 2 and
shows the cross-sectional detail of a lug assembly.
FIG. 4 is a view similar to FIG. 2 and shows the outfeed escapement
mechanism as it is indexed, thereby metering one piece to a
downstream process.
FIG. 5 is another view similar to FIG. 2 and shows the outfeed
escapement mechanism as the next incoming lug assembly impacts the
stops on the rotatable escapement wheel.
FIG. 6 is a detailed end elevation view of the outfeed end showing
an outfeed escapement mechanism.
FIG. 7 is a perspective view showing several lugs accumulated at an
outfeed escapement mechanism.
FIG. 8 is a view similar to FIG. 2 except showing the infeed
escapement mechanism.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring first to FIG. 1, a general description will be given to
specify the major structural and functional features of the
crowding lug transfer conveyor system, which is generally indicated
at 10. The infeed end of the transfer conveyor is generally
indicated at 12 and, in the embodiment shown, has elongated pieces
14, such as unedged sideboards generated from an upstream primary
breakdown station (not shown), being fed to conveyor system 10
longitudinally. The boards 14 are fed linearly in the direction of
flow arrow 16 by any suitable conveyor 18. A last feed roll 20
provides the final longitudinal conveying means to direct each
incoming piece onto conveyor system 10. The structure 22 provides
support surfaces 24 for each piece to impact and slide on until
they rest atop transfer conveyor 10. A plurality of cutouts 26 are
provided in upstanding backwall 28 in order to accommodate the
travel of the lugs, each indicated generally as 30, as a set is
indexed ahead of an incoming piece.
In the sawmill application, dimensional and structural requirements
will be determined based primarily on the length and width of the
boards to be handled and conveyed by the system. For example, in a
typical sawmill, side boards coming from the primary breakdown
station can be on the order of 8-24 feet in length and 3-24 inches
in width. As pointed out in the background, a substantial number of
side boards are generated in a typical high speed mill and the
handling systems must be capable of effectively accepting,
conveying and outfeeding the required number. In addition, since
the individual pieces can vary greatly in their dimensions, the
handling system must be versatile enough to handle pieces of the
dimensional ranges expected. While the embodiment depicted shows
boards 14 flowing longitudinally to infeed end 12 for lateral
transfer, the boards could also approach infeed end 12 from a
transverse direction as will be apparent to those skilled in the
art. It is also apparent that for elongated pieces a plurality of
sets of lugs 30 will be necessary with the sets being spaced
apart.
Spaced transversely from infeed end 12 a distance sufficient to
provide the functional requirements, as will become apparent, is
outfeed end generally indicated at 32. At outfeed end 32, a
plurality of pieces 14 are shown where they have been accumulated
and crowded in spaces provided by sets of lugs 30 as will be
further described. As pieces 14 are called for by the downstream
process station, generally indicated at 34, the outfeed indexing
means on transfer conveyor system 10 is activated to meter an
individual board from outfeed end 32. As depicted, process 34
represents a scanning station where each board is electro-optically
scanned to determine its dimensions. An overhead scanning frame 36
supports a portion of the scanning system and a pair of pin stops
38 can serve to hold the board during actual scanning. A typical
transfer conveyor 40 comprised of endless chains 42 on sprockets 44
mounted on spaced shafts 46, 48 serves to convey the individual
pieces 14 as they are metered from outfeed end 32 to the scanning
station. The sprockets on shaft 46 will usually be idler sprockets
while those on shaft 48 will be driven. From the scanning station,
the board is then directed to the downstream edging station (not
shown) where its rough edges are removed, the edging lines having
been determined through the scanning system and a computer
implemented decision and control system. Usually the boards will be
fed linearly through the edging station after they are scanned and
positioned relative to the edging means.
The crowding lug transfer conveyor 10 is comprised of a
substantially typical conveyor surface 50 consisting, in part, of a
plurality of spaced endless chains 52. The top flight of chains 52
forms a conveying plane atop which the pieces 14 will be supported
and conveyed. Flow arrows 54 indicate the direction of flow.
Endless chains 52 are trained about sprockets 56 which are mounted
on spaced shafts 46, 58. The sprockets 56 are fixedly mounted on
shaft 46 and are rotated through shaft 46 which is powered by motor
60 and driven means 62. In the usual operating mode, motor 60 will
continuously turn shaft 46 to continuously drive chains 52. The
sprockets 56 mounted on shaft 58 will be idler sprockets. As pieces
14 are conveyed transversely atop conveyor surface 50, an even
ending belt 64 is continuously operating to position each piece
with one end on a common plane. Any commercially available
even-ending means can be used to accomplish the function.
Still referring to FIG. 1, a plurality of endless lug conveyor
chains 66 are spaced from each other and from endless chains 52.
Chains 66 are trained about sprockets 68 which in turn are mounted
on spaced shafts 70, 58. Sprockets 68 on shaft 58 are idler
sprockets, not being driven by the shafts on which they are
mounted. The sprockets 68 on shaft 70 are driven as will be
explained. Each sprocket 68 has a diameter which is sized so that
the top flight of each lug chain 66 forms a horizontal plane that
is slightly below the plane of conveying surface 50. The length of
lug conveyor chains 66 determines the dimension of transfer
conveyor 10 between infeed and outfeed ends 12, 32. Serving to
drive lug conveyor chains 66 is motor 60. Drive shaft 46 is
interconnected through a suitable chain drive and sprocket means
(not shown) to sprockets 68 providing rotational movement to them.
Drive sprockets 69 (see FIG. 6), fixed to the sprockets 68 on shaft
70, are driven thereby turning sprockets 68. Each endless chain 66
will travel at a speed substantially equal to the speed of chains
52.
Positioned below and in line with each sprocket 68 on shaft 70 are
chain tensioning devices, each indicated at 72. In the embodiment
depicted, the device is shown as being a pneumatically loaded
sprocket wheel 73 around which its respective endless chain 66 will
travel. While it is desirable to provide a continuous tensioning
means for the lug chains 66, it is not absolutely necessary and
will not be further described.
Turning now to FIGS. 2-8, a detailed description will be given of
the lugs 30 and their feeding, transfer, and indexing structure.
Each lug chain 66 has a predetermined number of lugs slideably
associated therewith. As an example, in the application where side
boards are being conveyed by conveyor system 10 from a primary
breakdown station to a downstream processing station, thirty lugs
have been determined adequate to provide the desired capacity. The
transfer distance from shaft 58 to shaft 70 and the desired spacing
between pieces will determine the number of lugs for the particular
application.
Each lug has a body portion 74 through which chain 66 can slideably
travel. The chain passage is generally indicated at 76 in FIG. 3.
The body length is predetermined and is based on the average
largest width piece that must be transported by the transfer
conveyor. Even if an occasional piece is wider than the body
length, the system is capable of functioning in the intended
manner. Extending upwardly from the leading end of each lug body 74
is the upstanding lug member 78. Lug members 78 extend upwardly
above the plane of conveyor surface 50 a distance that is
approximately one to two times the thickness dimension of the
pieces being handled and transferred. Laterally spaced at each end
of lug body 74 is a pair of opposed guide pins, each pin being
indicated at 80. The guide pins 80 are attached to the outer sides
of body 74 and serve, in part, to support and guide each lug during
its travel along the upper run of chain 66. A pair of guide
channels or other suitable guide means, each indicated at 81,
extend from the infeed to the outfeed end along each side of lug
chain 66 and serve to support and guide the pins 80 as a lug
travels.
Pivotally mounted within each lug body 74 on support pins 83 and at
each end are opposed chain caliper blocks, each indicated at 82.
The caliper blocks 82 are designed to engage, on a continuous
contact basis, the endless chain 66. Serving to cause continuous
engagement of the caliper blocks 82 with lug conveyor chains 66 are
biasing springs 84 mounted within the hollow portion 86 of pins 80.
Springs 84 exert a calipering force about chains 66 at the leading
and trailing ends of the lug bodies. The force, approximately 2-6
lbs., is sufficient to cause a frictional gripping action on chain
66, causing the lug to travel with the lug chain along guide
channels 81. The engagement pressure is, however, designed to allow
the chain to continuously slide through the caliper blocks 82 when
a holding force is applied to a lug as will become more apparent
shortly. It has been determined that a suitable material offering
long wear characteristics for caliper blocks 82 is a commercially
available ultra high molecular weight polyethylene composition. It
can be machined and wears well from lug chain sliding contact.
Turning now to a description of an outfeed indexing and metering
assembly or escapement mechanisms, each generally indicated at 88,
particular reference will be made to FIGS. 1, 2, and 4-7. As can be
seen in FIG. 1, in a sawmill application for the transverse
crowding and conveying system, there are four separate metering
assemblies at outfeed end 32. Each assembly 88 is driven from
common shaft 70 through a motor 90 and indexing driven means
92.
Fixedly mounted on shaft 70 are spaced pairs of escapement plates,
each plate indicated as 94. A pair of plates 94 is mounted near
each side of a sprocket 68 on hubs 96 and are fixed to shaft 70
with a key assembly generally indicated at 98. As can be seen when
referring to FIG. 6, sprockets 68 are mounted on shaft 70 with
bearings 100 so they are free to rotate independently of plates 94.
A modularized structure as depicted in FIG. 6 can be provided with
supporting structure 102 holding chain tensioning devices 72
together with sprockets 68 and escapement plates 94. Shaft 70 will
be split between metering assemblies with couplings 104.
Each plate 94 is designed to provide a plurality of uniformly
spaced holding and conveying units 106 functional to first hold and
then convey and release one pin on one side of a lug 30. Units 106,
as depicted in the Figures, are so positioned on their respective
plates so that in each pair of plates on either side of a sprocket
68 they are laterally in line in order to act on the forward two
pins 80 on each side of a lug 30. Each plate is sized and
structured to provide a plurality of forward impact and holding
areas 108 which, in the embodiment depicted, include the spring
loaded latching mechanisms 110 for positive conveying. At the back
end 112 of units 106 is rear impact and pusher member 114 designed
to impact and push a back pin on lug 30. A pair of members 114 will
impact the pair of opposed back pins on a lug and index the lug
around the metering assembly to a position where it will be
released to travel with its lug chain back to the infeed end
12.
At the infeed end 12 (an infeed indexing assembly is depicted in
detail in FIG. 8) a plurality of lugs 30 will be accumulated on the
bottom run of a lug chain 66 with the chain continuously passing
through caliper blocks 82. When boards 14 approach conveyor surface
50, a set of lugs will be released or indexed each to travel on its
respective lug chain ahead of each board before they individually
come to rest atop surface 50. The infeed indexing assemblies or
escapement mechanisms, generally indicated at 116, are constructed
substantially similarly to outfeed metering assemblies 88. A
separate motor 118 and index drive means 120 rotate shaft 58 to
release lugs 30 at each infeed assembly 116 on command. At infeed
end 12, the lugs 30 are held below the plane of conveyor surface 50
until a set of lugs is released, at which time the upstanding
members 78 move upwardly to a position where they rise above the
boards and maintain the desired spacing between boards. Once
released, each lug chain 66 will carry its lug 30 until it impacts
the last accumulated lug at outfeed end 32. At outfeed end 32, a
plurality of separated crowded boards can be maintained in queue
and metered as needed by the downstream process by metering
assemblies 88.
While the operation of the invention is apparent from the foregoing
detailed description and drawings, a sequencing of elements through
a cycle will be described. Single boards are fed to conveyor
surface 50 at the infeed end 12. As a single board approaches
surface 50, a suitable detection means (not shown) will generate a
signal to cause motor 118 to index the infeed indexing assemblies
116 one position. One set of lugs 30 will be released and each lug
chain 66, through the force from caliper blocks 82, will propel a
lug down conveyor surface 50 ahead of the board. At outfeed end 32,
the traveling board will impact the upstanding members 78 of the
set of lugs which will be abutting the set of lugs accumulated and
held from the previous cycle. Each set of lugs that are accumulated
upstream from assemblies 88 will be uniformly spaced as determined
by the length dimension of lug bodies 74. Since chains 52 continue
moving, each board will abut and be crowded against the downstream
set of upstanding lug members 78. Lug chains 66 are also in
continuous motion and when the lugs are being held by the metering
assemblies, they slide through caliper blocks 82.
When the downstream process calls for a board, a signal is sent to
drive means 92 and shaft 70 is caused to rotate. The acceleration
is controlled through drive means 92 to move the last set of lugs
30 in a desired manner. Once the escapement plates 94 are rotated,
the set of lug members 78 holding the board to be metered are
caused to move downwardly, thereby releasing a single board.
Simultaneously, a set of lugs is indexed and released from the
metering assemblies. The lug chains and grasping caliper blocks
cause the released set to return to the infeed end. FIGS. 2, 4, 5,
7 and 8 depict the transfer conveyor system at various points in
its cycle.
While a detailed description of the invention and an operative
cycle has been given, it may occur to those skilled in the
conveying art to make modifications. All such modifications are
intended to be included within the scope of the appended
claims.
* * * * *